Decontamination of internal combustion engine exhaust gases and devices for the implementation of the procedures

ABSTRACT

Apparatus for decontamination of internal combustion engine exhaust gases by the preparation of a flammable and ignitable air-fuel mixture with a variable air ratio figure lambda by means of a throttle flap adjustment for regulating the fuel jet flow resistance, and which is adjustable such that fuel atomization is performed. This is accomplished by the fact that the airstream flowing from the air filter to the carburetor, particularly in the lower engine r.p.m. range i.e. if the throttle flap swivel range is small, is accelerated in the crescent-shaped gap between throttle flap (10) and carburetor duct wall (20), on the whole throttle flap semi-circumference facing the fuel jets, to nearly sonic or supersonic speed. Furthermore, at the throttle flap swivel range in the medium engine operating range at subsonic speed, the air stream flowing from the air filter to the carburetor is additionally accelerated by further jet effect, whereas the airstream from the air filter to the carburetor in the operating range up to full engine load is homogenized by very intensive elimination of the turbulence.

United States Patent 1 Lang [ Sept. 18, 1973 [75] Inventor: Ludwig G.Lang, Darmstadt,

Germany [73] Assignee: Ingeuieuburo Fur Angewandte Physik und Chemie,Darmstadt, Germany 22 ,Filed: June 30, 1970 21 Appl.No.:51,163

[30] Foreign Application Priority Data July 3, 1969 Austria 6390/69 Aug.6, 1969 Austria 7589/69 Nov. 10, 1969 Austria 10547/69 [52] US. Cl.261/41 D, 261/65, 261/47,

[51] Int. Cl. F02m 23/02 [58] Field of Search 261/41 D, 65

[56] 1 References Cited UNITED STATES PATENTS 1,842,866 l/l932 Goudard261/41 D 1,863,715 6/1932 Heitger 261/41 D 1,868,831 7/1932 Heitger....261/65 2,080,440 5/1937 Scott 261/65 2,035,191 3/1936 Reynolds 261/652,271,390 1/1942 Dodson 261/65 2,383,697 8/1945 Wassman..... 261/652,680,592 6/1954 Zierer 261/65 3,047,277 7/1962 Landrum 261/65 3,298,677l/l967 Anderson 261/41 D 3,304,068 2/1967 Thomas 261/41 D 3,408,05410/1968 Walker 261/41 D 3,414,242 12/1968 Bouteleux 261/41 D 3,057,60610/1962 Henga 261/65 FOREIGN PATENTS OR APPLICATIONS 266,734 2/1927Great Britain 261/41 D 33,732 9/1924 Denmark... 261/41 D 747,193 6/1933France 261/41 D Primary Examiner-Tim R Miles Attorney-Woodhams,Blanchard and Flynn [57] ABSTRACT Apparatus for decontamination ofinternal combustion engine exhaust gases by the preparation of aflammable and ignitable air-fuel mixture with a variable air ratiofigure )t by means of a throttle flap adjustment for regulating the fueljet flow resistance, and which is adjustable such that fuel atomizationis performed. This is ac complished by the fact that the airstreamflowing from the air filter to the carburetor, particularly in the lowerengine r.p.m. range i.e. if the throttle flap swivel range is small, isaccelerated in the crescent-shaped gap be tween throttle flap (10) andcarburetor duct wall (20), on the whole throttle flap semi-circumferencefacing the fuel jets, to nearly sonic or supersonic speed. Furthermore,at the throttle flap swivel range in the medium engine operating rangeat subsonic speed, the air stream flowing from the air filter to thecarburetor is additionally accelerated by further jet effect, whereasthe airstream from the air filter to the carburetor in the operatingrange up to full engine load is homogenized by very intensiveelimination of the turbulence.

24 Claims, 21 Drawing Figures PATENTEU 81975 3 759 499 SHEET 1 m 6 NOXCH ppm 3000 700 Wi wam/Z1,

Aim/Wm? PATENIEU SEP] 8 ms SHEET 2 DF 6 INVENTOR I B [HOW/6 G. [AA/6 %/W6 9% PATENTEUSEH a ma 3,

sums 0F 5 MA W 1/ PATENTEnsm a ma SHEET 5 BF 6 FIG. '18

FIG.17

120 km/h IN V EN TOR 5 1 W a. U 4 MM w 16 B PAIENTEU SEPI a ma SHEET 6BF 6 FIG. 20

ws 8000 Q) FIG.21 Q

cm /sec D=30mm V=1m/sec INVENTOR lllfil V/ 6f AAA/6 MKMMV%W DEVICES FORTHE IMPLEMENTATION OF THE PROCEDURES This invention relates to bothprocedures for decontamination of internal combustion engine exhaustgases by preparation of a flammable and ignitable air-fuel mixture, witha variable air ratio figure A adjustable by a throttle flap regulatingthe hydraulic resistance in the fuel jets which is adjustable in such away that fuel atomization is performed and to devices for theimplementation of such procedures.

As is generally known internal combustion engine carburetors have astarter flap, throttle flap, idling fuel jet, main fuel jet, and asupplementary jet for reaching maximum performance during full-speedoperation.

The air-fuel ratio in the air-fuel mixture is expressed by A which, e.g.in FIG. 1 is used as abscissa for plotting the composition of theCO-CI-I and NO, portions, and with respect to the path of the effectivemedium pressure (psi) A=1 being the stoichiometric air: fuel ratio 14.81.

The starter flap and throttle flap control'the carburetor hydraulicresistance against the fresh air stream to the engine and/or internalcombustion engine. The starter flap provides for reducing of the airportion in the air-fuel mixture during starting, and thus leads to arich mixture.

The task of the throttle flap is to regulate the mixture flown throughby influencing the functioning of the various fuel jets.

Upon closing the throttle flap, a high vacuum of about 5 6,000 mm WSresults in the inlet manifold and causes the idle jet to operate. Inorder to void stalling of the engine, a relatively rich mixture of e.g.A 0.95 is provided. If the throttle flap is further opened, the mainfuel jet equipped with a venturi-arrangement starts operating andsupplies a mixture with a mainly constant and relatively high air-fuelratio of A 1.0.

During full speed operation the pressure drop on the fully openedthrottle flap is reduced to about 3,500 4,500 mm WS. Thereby thesupplementary fuel jet is operating and supplies the engine with a muchenriched air-fuel mixture.

In case of a multi-cylinder engine, smooth running can only be reachedif all cylinders operate properly and without combustion interruptions,as e.g. can be caused by a partial air rarefaction.

' In case of a reduction of the total mixture, as required by theexhaust gas decontamination requirements and regulations, that cylinderwhich receives the poorest mixture, due to non-uniform mixturedistribution, will first start to operate irregularly, The morenon-uniform the mixture distribution of an engine, the

less is the possibility of a reduction of the total air-fuel mixture. Inthe main, therefore, it is important that for getting a steady flamefront formation and flame front propagation speed in each cylinder of aninternal combustion engine, a widely homogenized and flammable air-fuelmixture is supplied.

It is known that e.g. warming up of the suction tube wall following thecarburetor, has an influence on the air-fuel mixture just like thecarburetor and suction tube forms. Even in case of small heated areas,heatingup eg by means of exhaust gases leads to an evaporation of themost part of the liquid fuel flowing along the walls.

In particular, the invention relates to the procedures of a homogenizedmixture production and distribution in the carburetor, and in particularin the area of the throttle flap and its forms, taking intoconsideration the flow developments in the carburetor with the effectson the hydraulic resistance for the fuel flow on the various jets.

The'task of the invention is to largely decontaminate internalcombustion engine exhaust gases and to form carburetors andsupplementary devices for carburetors in such a way as to guarantee awidest possible decontarnination of internal combustion engine exhaustgases.

As is generally known, the gas flow speeds in the cross sections of thefresh air supply from the air filter to the carburetor and behind thecarburetor for the airfuel mixture in the suction tube to the cylinderreach a speed of as much as 0.15 and 0.2 Mach, at Reynolds numbers of upto 1.0 X 10 and/or 1.5 X 10 i.e. in the range of aerodynamics, so thatflow processes can be handled according to the basic equations forincompressible flows.

The situation is completely different in the throttle flap area. If thethrottle flap is nearly closed, speeds in the sonic range occur in thenarrowest areas of the crescent-shaped gaps between throttle flap andcarburetor tube bore as a result of the great differences in pressure.In that flow range of the throttle flap the equations for compressibleflows, both for the Bernouillis and for the continuity equation have tobe applied.

The task of the invention is solved by the fact that, for thedecontamination of internal combustion engine exhaust gases bypreparation of a flammable and ignitable air-fuel mixture with avariable air ratio figure A by means of a throttle flap adjustmentregulating the hydraulic resistance in the fuel jets, and which isadjustable such that fuel atomization is performed, a procedure isapplied in which the airstream-speed flowing from the air filter to thecarburetor, particularly in the lower engine rpm. range, i.e. if thethrottle flap swivel range is small, is accelerated in thecresent-shaped gap between throttle flap and carburetor duct wall on thewhole throttle flap semi-circumference facing the fuel jets, to nearlysonic or supersonic speed, and that furthermore, at the throttle flapswivel range in the medium engine operating range, at subsonic speeds,the air stream flowing from the air filter to the carburetor, isadditionally accelerated by jet effect in the throttle flap area,whereas the air stream from the filter to the carburetor in theoperating range up to full engine load, is homogenized by very intensiveelimination of the turbulence.

To effect this, appropriate additional air is supplied to the air-fuelmixture, streaming ofi from the throttle flap area, in a variable Avariation for the purpose of reduction in accordance with the operatingstage intervals of an exhaust gas decontamination law, whereas the fuelfilm depositing on the carburetor tube wall, no matter whether in theform of a condensate or as slowly evaporating fuel composites from thethrust strokes is subjected to a time-delayed post-carburetion.

Moreover, the air-fuel mixture flow, flowing off from the throttle flaparea is divided into an internal and a wall channel flow, thetime-controlled supplied additional air being superimposed on the wallchannel in the form of a revolving flow, so that the more dense andslowly evaporating fuel composites being still liquid will remain in thefuel film streaming off.

The procedures and devices for implementation of the procedures,according to this invention, are closer outlined by examples and show:

FIG. 1 illustrates a diagram of the air-fuel ratio.

FIG. 2 Part-sectioned drawing of a throttle-flap and air-regulatingplate and/or static tube.

FIG. 3 Perspective view of a throttle flap.

FIG. 4 Part-sectioned drawing along line lV-IV of FIG. 3.

FIG. 5 Part-sectioned drawing along line V-V of FIG. 3.

FIG. 6 Perspective view of a throttle flap of another type.

FIG. 7 Part-sectioned drawing along the line VII- VII of FIG. 6.

FIG. 8 Part-sectioned drawing along the line VIII- -VIII through astatic tube upper section of FIG. 9.

FIG. 9 Static tube upper section top view.

FIG. 10 Part-sectioned drawing along the line XX of FIG. 11.

FIG. 11 Static tube lower section top view.

FIG. 12 Air regulating plate top view.

FIG. 13 Part-sectioned drawing along line XIIIXIII of FIG. 12.

FIG. 14 View of a fresh air supply unit with drain tube.

FIG. 15 Part-sectioned drawing along line XV-XV of FIG. 14.

FIG. 16 View of the roller guide of a fresh-air supply unit enlargedscale.

FIG. 17 Side view of a fresh-air supply unit in the form of a segmentlever.

FIG. 18 Front view according to FIG. 17.

FIG. 19 Segment lever enlarged scale.

FIG. 20 Diagram showing the relation between pressure and engine r.p.m.

FIG. 21 Diagram showing the portion of flow stream in relation to theair ratio figure A, at a D- mm throttle flap diameter and a mixture flowspeed V FIG. 1 clearly shows the functional requirements of an exhaustgas decontamination system. For reasons of smooth engine runningconditions during idling, of good starting quality and of a goodperformance in the other engine r.p.m. ranges the idling adjustment issuch that the air ratio figure A is between 0.9 and 1.0, preferably at0.95. In order to reach an exhaust gas decontamination within the limitsof an exhaust gas decontamination regulation, a reduction of the fuelportion in the air-fuel mixture to A 1.1 to 1.15 must be performed. Withmost four-stroke engines of the state-ofthe-art stutter-free running isstill possible with a reduction to that degree. In order to comply withthe requirements of an exhaust gas decontamination law, with regard to areduction of the NO; composites, the then necessary air-fuel ratioadjustment would require a reduction of the fuel portion in the air-fuelmixture to 1.25 and 1.3. No state-of-the-art four-stroke engine permitsa reduction to such a degree. To effect this, a costly andtime-consuming new engine development would be required. Moreover, thisalso required addition of a catalytic operating afterburner i.e. partialdecontamination actions must take place as a result of measures beforeand after the cylinder.

Of decisive influence in all these measures is that a carburetor oradditional devices to a carburetor of the state-of-the-art, can no morebe adjusted after installation in those parts, serving such measuresi.e. which effect a reduction of the mixture in the r.p.m. rangedemanded in the exhaust gas decontamination law.

This is an important requirement for the executive orders of an exhaustgas decontamination law.

These requirements are also met by the invention procedures and devicesfor implementation of these procedures for exhaust gas decontamination.

FIG. 2 shows an additional device for a state-of-theart carburetor, inthe form of a throttle flap 10. It has ring-shaped rims l1 and 12, whichare of protruding form at 14 and at least partially blocks the bypassjets 20A and thereby cover the effective operating range of the bypassjets 20A in the carburetor duct 20. A sniffle valve 110 can also bearranged at that side of throttle flap 10 which is free of rims.

Moreover, an air regulating plate 30 will be arranged below a standardstate-of-the-art carburetor, having inserts and 104 for the purpose offorming a ram jet with post carburetor effect. This air regulation plate30 possesses a lateral, preferably jet-formed bore 39 for the supply offresh air regulated by a fresh air transmitter.

The distances in carburetor duct 20 which can preferably be usedflow-technically for the mixture formation at little swivel angles, areidentified as a and b, with the possibility of producing both goodsurface finish and fit or distance a, between carburetor duct 20 andthrottle flap 10, whereas distance [1 has a greater surface roughness,which can, if required, later on be roughened up to knurled-roughness inorder to produce a wave form with Mach-angle sin a l/M characteristicsparticularly if a transsonic flow occurs, or in the supersonic case M g1.

Throttle flap 10 has a smaller dia. d than the inner dia. D ofcarburetor duct 20, whereby an annular clearances as shown on FIG. 4 isformed and guaranteed, which results from the determination of theidling r.p.m. and the idling jet bore 208 selected.

To guarantee the functioning of a standard carburetor for formation ofan optimum mixture with respect to a large exhaust gas decontamination,the fit quality of this clearance s is determined according to the ISAsystem-of-fits. Due to this tolerance an additional air adjustmentscrew, as provided in many cases, is no more required.

As can be seen from FIG. 3, the ring-shaped rims 11 and 12 are onlyarranged around half of the circumference of throttle flap l0, namely inthe idle-jet bore 20B area and bypass-jet bore 20A area.

According to FIGS. 6 and 7, the ring-shaped rims 11 and 12 can alsoextend over half of the throttle flap circumference. This version can beof importance to multiple stage carburetors in the bore of the secondstage which becomes effective only at a speed which is higher than thatof the idling r.p.m. In such a case the ringshaped rims l1 and 12 cane.g. be of such a form that the height of the rim is determined by'theswivel angle position by arranging the maximum elevation at that sidepointing upwards, whereas the elevation goes down to about zero at thatside pointing downwards.

tween the spherical-shaped rim surfaces and the carbu-.

retor duct bore 20 is not to increase beyond that existing at the idlingr.p.m. adjustment for the swivel angle.

In the medium performance range of the engine for swivel angles of about15 to 45 or 55, depending upon the marginal values of an exhaust gasdecontamination test, the spherically formed rim backs have still astrong jet effect at the side of the bypass-bores 20A. Therefore speedsinto the transsonic range will occur at that half circumference ofthrottle flap with a crescent-formed gap, down to the fit tolerance ofidling r.p.m. a 0, so that the fuel film preferably consisting ofreluctantly evaporating fuel portions is exposed to influences of theboundary layer of the flow. The inner friction during these high speedsis due to the low pressure present in that throttle flap range. They arealso an asset for the preparation of the fuel film. A further additionis the displacement effect of the high speed.

If, as proposed, a smooth-surface wall is produced along distance a ofthe carburetor duct (FIG. 2) for reasons of fit, gradually passing intoa rough surface, along distance b, so the fuel film on distance a willbe rapidly forced away and will be decelerated on distance b. On thisrough surface of distance b a wave form occurs in this boundary layerarea, with the Mach angle sin a l/M which is relevant at these highspeeds. The spreading is all over the carburetor duct, with reflectionson the respective opposite wall. An intensive homogenized mixture isformed. Since fuel atomization primarily depends on the gas-fluidrelative speed a super-atomization occurs in this area of swivel rangeof throttle. flap 10, which is of importance for further transport tothe cylinder.

The inner surface form of rim 12 on throttle flap 10 has aparticularfunction in this swivel angle range. It

is to change the ram pressure area on the upper surface of throttle flap10 both in size and form. The inner rim area can get a gradualtransition to the plate thickness of throttle flap 10.It is preferableto provide a steep gradient on rim 12 at the inner side, at best with anangle of 50 60. Thereby a local flow deflection occurs in the area ofthis abruptly sloping-down back of rim 12, which, due to its thrusteffect, over the downward-pointing side of throttle flap 10 permitsflowing off of an increased portion of the impact flow via thecrescent-formed gap. The effect of this increased portion of flow. isshown on FIG. 21 diagram.

This swivel angle range of flap 10 is within the motor vehicle speedrange for which an exhaust gas decontamination is required. Theaerodynamic design of throttle flap 10 contributes a portion of areduction of the air-fuel mixture in the sense of a A variation.

The rims 11 and 12 possess fine, jet-like bores 15. Their effect in thethrottle flap swivel angle range described is such that they contributeto reducing the ram pressure field over the throttle flap, because thereis a low pressure field over the outside of the rim back, due to the jeteffect. This suction effect also brings about a removal of a portion ofthe congested flow on the upward-pointing half of throttle flap 10.

The rims 11 and 12 cause a different effect in the load range up to fullload of the engine. In the case of swivel angles up to 90 the first flowpath around the outside of the throttle flap breaks off at the sharpcorners of the rim backs to define a vortex generator. The sphericalform of the 2 rim backs, which become efiective in this swivel anglerange, have the advantage over a disc-shaped throttle-flap of thestate-of-the-art, that a ram point can form, which determines theflowing off.

As has already been mentioned, the rims 11 and 12 have fine jet-likebores 15. These fine bores define a second streamlined path for the airand produce thin flow lines of high-speed air which remove quickly thevortex trains which leave the sharp edges 17 of the rims 11 and 12.

This strong turbulence has a homogenizing effect on the mixtureformation in this swivel angle range of throttle flap 10.

In the evaluation of the various operating stages of an exhaust gasdecontamination test the delayed thrust re qui'ring only a shortoperating time has a great influence on the total result of an exhaustgas decontamination measure. This influence is minimized by keeping thehigh fuel thrust low. The fuel flow from the bypass jets can be reducedby quick build-up of a hydraulic resistance.

In the area of the bypass bores 20A the upper rim 1 l of throttle flap10 will be provided with a protuberance-like, locally limited elevation14, having, at a swivel angle 0, the fit of throttle flap 10 to thecarburetor duct. Rapid swivelling back of throttle flap 10 causes justas rapid build-up of a hydraulic resistance for the bypass jets, whichconsiderably reduces the fuel flow.

The flow in the throttle flap area permits, particularly for the delayedthrust, a generally known measure. A snifile valve 1 10 can be providedat the rim-free side of throttle flap 10, over which a ram pressure isalways effective in the medium swivel ranges of throttle flap 10.

During rapid swivelling back of throttle flap 10 in the delayed thrustthe sniffle valve opens and thus further contributes to increasedflowing-off of the flow in the throttle flaparea.

The changes due to aerodynamics, as described before, in the flowing-offof the air-fuel mixture in the area of the throttle flap, are notsufficient to fulfill the requirements of an exhaust gas decontaminationtest. Their importance is particularly in the production of a stronglyhomogenized mixture-format. The effect of an aerodynamic-formed throttleflap 10 was investigated by low-pressure measurements, whereby thepressures on bore 38 in FIG. 18 were measured with and withoutadditional air over segment lever 40 in FIG. 19. The

Curve 3: Throttle flap provided with the invention characteristics,without additional air over segment lever 40.

Curve 4: Throttle flap provided with the invention characteristics withadditional air over segment lever 40.

These measurements show that due to special influences of the throttleflap characteristics in various throttle flap swivel ranges, aflow'speed increase has occurred, which is an explanation for the lowpressure difference. This small low pressure potential has aresistance-balancing effect in the turbulent air-fuel mixture flow inthe carburetor duct. In that case the experimental engine is runningremarkably smoother.

I Small amounts of additional air must be introduced during theoperating stages of an exhaust gas decontamination test run in the uppermotor vehicle speed limits e.g. in the U. S.- California test up to 80km/h and Europe test up to 50 km/h, in these engine r.p.m. ranges. Thisintroduction must take place according to the requirements of thesyncrho-operational stages and the thrust intervals with theirrespective operating times. The time influence is synchronized with thethrottle flap 10 movement by coupling the control linkage of the freshair regulating arrangement with the shaft of throttle flap 10. Theamount of air required according to the time intervals is introduced bya flat guide which can be formed as a roll guide 73 (FIG. 14-16) orsegment guide and/or an envelope curve 43 and 44 (FIG. 17-19).

First of all, an air regulating plate 30 will be arranged under thecarburetor, Its inner dia. D is that of the carburetor duct. Moreover;air regulating plate 30 is the carrier of a ram jet consisting of parts100 and 104 (FIG. 2, 8-11).

The upper part 100 of the ram jet has a preferably conical inner wall101, connected with a ring bearing. This arrangement can, depending onthe case, also be one integral component. The ring bearing 102 possessesthe cutouts 103, letting through the wall duct stream.

The lower part 104 also has a preferably conical inner wall 105, wherebythe conicalness of the cone shell can either be the same as the upperpart 100, or of tapered form towards the outlet. This cone shell 105 isconnected with an intermediate cone shell 106 the tapered form of whichis in the same direction, with a small space remaining in between. Thisintermediate shell 106 has a ring bearing 107. A ram jet is formed withparts 100 and 104, representing a basic measure for carburetors bydividing the air-fuel mixture flow from the throttle flap 10 area in aninner and in a wall flow.

' As is generally known, the fuel film on the wall of the carburetorduct and on the following suction tube wall has a disturbing effect onthe mixture preparation. This fuel film can deposit as condensate on thewall, or can form particularly in the delayed thrust interval. It mainlyconsists of the reluctantly evaporating portions of the total fuel. Partof the fuel film evaporates due to the influence of the low pressurefield in the throttle flap 10 area, so that the wall stream is richerthan the internal stream in the mixture flow. This discovery leads totwo measures for exhaust gas decontamination: the reluctantlyevaporating portions of the total fuel with larger density are, due tothe displacement eflect in the flow boundary layer, particularly at highflow speeds, forced away into the narrow space between the cone shells105 and 106 of the jet lower part 104, which thus becomes the collectingpocket for the liquid portions of the fuel.

Bores 108 are arranged in the cone shells 105 and 106 of the jet lowerpart 104, which both by their size and position to the bottom of thecollecting pocket will be aligned such that this accumulating liquidfuel portion will be subjected to post-atomization. This effects a timeshift in the preparation of the fuel film during the operating stage. Inorder to fulfill the requirements of an exhaust gas decontamination lawthis time shift of the preparation of the liquid reluctantly evaporatingportions of the total fuel can be used for unloading of the operatingstage, which is of great significance in the test.

The second measure concerns introduction of the additional air through alateral bore 39 in the air regulating plate 30 which preferably will beformed jet-like. This bore 39 enters tangentially inner bore 32 of airregulating plate 30. The additional air is only blown into the gapbetween the jet upper part 100 and lower part 104. This additional airprimarily exercises an effect on the wall channel stream which entersvia cutout 103 of ring bearing 102 of the jet upper part 100.

The introduction of additional air according to the operating stages viaa fresh air transmitter can be performed as follows. This procedure willbe outlined by two examples.

FIGS. 14 to 16 show a fresh air transmitter 70. It consists of a housing71 with a bearing or support bracket 72 for the purpose of attachment tothe carburetor 21. Inside housing 71 there runs a preferablyselfsupporting roll guide 73, which is presented in FIG. 16 in enlargedscale. This roll guide 73 has a lug 74, by which it is supported inhousing 71 and on which a lever 75 will be attached. A preferablyadjustable linkage 77 is connected to this lever 75, being theconnection to lever 46. Lever 46 is connected with the throttle flapshaft 23. This so-arranged operational linkage between fresh airtransmitter and carburetor guarantees a synchronous adjustment of rollguide 73 with throttle flap shaft 23.

As can be seen from FIG. 15, a fresh air transmitter tube 78 is screwedinto housing 71, which is closed at the air entry by a thin-mesh filter79 and secured by the perforated cover 82. Opposite the fresh airtransmitter tube 78 a tube 83 is attached in housing 71, through whichthe additional air to the air regulating plate 30 will be removed viathe lateral bore 39. The distance between fresh air transmitter tube 78and drain tube 83 can be adjusted by the thread 85 or the fresh airtransmitter tube 78 to housing 71.

Roll guide 73 possesses two cutouts on the cylinder surface. A largecutout 86 for the swivel movement of roll guide 73 in housing 71 in thearea of the fresh air transmitter tube 78 and a guide-type cutout 87,the size and form of which is determined by the amounts of fresh airrequired in the individual operating stages of an exhaust gasdecontamination test.

As can be seen from FIG. 14, the fresh air transmitter 70 is connectedto the air regulating plate 30 e.g. by a hose 84. A further fresh airtransmitter is shown in FIGS. 17 to 19.

The air regulating plate 30 is closed at the end of bore 39 and has abore 38 which is offset by 90. A thinmeshed filter 51 is inserted inthis bore 38. A segment lever 40 is connected to the control linkage ofcarburetor 21 at 41 thus bringing about a synchronized motion of segmentlever 40 with the throttle flap shaft 23 during passing over the lateralbore 38 located in the air regulating plate 30. Segment lever 40 canpossess a guide for the additional air in the form of a segment levercutout, a better solution, however, is an envelope curve 43, determiningthe amount of additional air for the individual operating stages of anexhaust gas decontamination test. The envelope curve 43 on segment lever40, shown in FIG. 19 is adapted to the USA- California test. Forconstant operating stages e.g. for the constant operating stage at 48km/h of the motor vehicle, a special stop 44 can be arranged, which isof no detrimental effect in the thrust operating stages during passingover envelope curve 43 above lateral bore 38.

The design of the fresh-air-transmitter to be adopted depends on thecarburetor construction and on the space available in the enginecarburetor area.

It is a known fact that the exhaust manifold of the motor vehicle can befollowed by a catalytic-action afterburner, for the purpose of achievingin particular a reduction of the nitrogen oxide portions NO, present inthe exhaust gas of an i.c. engine. If the heterogeneous catalysis isapplied for the nitrogen oxide portion NO, reduction, the reductiontakes place according to the equation 2 C 2 NO a 2 C0; N but only then,if the free oxygen 0, in the exhaust gas stream is low e.g. 0.5 to 1.5vol.%.

This requirement for a reduction of the nitrogen oxide portions requiresvery precise rating, also of the additional air supply, in the range ofthe exhaust gas decontamination laws.

The design of a fresh air transmitter as a roll guide or segment leverwith envelope curve or guide cutout enable the rating of the additionalfresh air amount with such a precision that the reduction requirementsfor a post-catalytic reduction process of the nitrogen portion NO, canbe fulfilled.

The procedures and constructions of a carburetor described, or theadditional devices to a carburetor of the state-of-the-art result in a)t-variation of the air-fuel mixture which can be adapted to theregulations of an exhaust gas decontamination law and which is effectedpurely flow-technically. The characteristic devices of the invention areinside a carburetor and cannot be seen and adjustedfrom the outside.Also the outside fresh-air transmitter is locked. The devices can bemanufactured economically and can be mounted correctly without specialknowledge and special tools. This. exhaust gas decontamination systempresents no problem to workshop and customer and thus facilitates theexecutive orders of exhaust gas decontamination laws.

I claim:

1. Apparatus for decontaminating the exhaust gases produced by aninternal combustion engine by atomizing the fuel and varying theair-fuel ratio figure A, comprising:

means defining a carburetor duct;

a throttle flap in said carburetor duct means for accelerating theair-fuel mixture flow past said throttle flap along a first path;

rim means on said throttle flap adjacent the periphery thereof forgenerating a vortex on the downstream side of said throttle flap alongsaid first P means defining at least one bore in said rim means foraccelerating said air-fuel mixtureflow in a streamlined manner past saidthrottle flap in a second path intersecting said first path to effect anelimination of said vortex and thereby provide a homogeneous mixture ofsaid air and! said fuel;

air regulating plate means arranged downstream of said throttle flapmeans for carbureting the fuel which has condensed on the wall of saidcarburetor duct; and

fresh air supply means for supplying additional air downstream of saidthrottle flap means.

2. Apparatus according to claim 1, wherein said rim means varies inheight along the length thereof.

3. Apparatus according to claim 1, wherein said rim means extends alongsaid periphery on one side of the axis of rotation thereof.

4. Apparatus according to claim 1, wherein said fresh air supply meanscomprises an opening in said air regulating plate means.

5. Apparatus according to claim 1, wherein the plane of said throttleflap is perpendicular to the axis of said carburetor duct means whensaid internal combustion engine is at said idling speed.

6. Apparatus according to claim 1, wherein said rim means include meansdefining a plurality of nonradial openings therethrough so that theupper portion of said rim means shifts a large amount of air as comparedto the flat portion of said throttle flap means due to an increased flowdeflection of the air-fuel mixture ratio A in the direction of A a 0.

7. Apparatus according to claim 6, wherein said rim means includes meansdefining a sharp edge for producing a vortex in said air-fuel mixturedownstream of said throttle flap means; and

wherein said bore means in said rim means produce streamlined jetsdownstream of said throttle plate means to eliminate said vortex andthereby cause a homogenization of the air-fuel mixture throughout thedownstream cross section of said carburetor duct means.

8. Apparatus according to claim 1, including a conventional bypass borein said duct means adjacent said throttle flap means and a protuberanceon the upper side of said throttle flap means and adapted to at leastpartially block said conventional bypass bore for the purpose ofreducing the fuel supply when said internal combustion engine is at idlespeed.

9. Apparatus according to claim 8, including a sniffle valve on saidthrottle flap.

10. Apparatus according to claim 1, wherein said fresh air supply meanscomprises a segment lever which can be actuated synchronously by aconnection with the operating linkage of the carburetor.

11. Apparatus according to claim 10, wherein said segment leverpreferably has an envelope curve for the throttle flap swivel rangewhich concerns the exhaust gas decontamination for the regulation of theamount of time-intervalled additional fresh air, whereby the idlingposition remains fully covered.

12. Apparatus according to claim 1, wherein said air regulating platemeans includes a pair of conically shaped upper and lower conduit means.

13. Apparatus according to claim 12, wherein said conically shaped lowerconduit means comprises a pair of concentric conically shaped conduitsdefining a gap therebetween; and

wherein the inner one of said conically shaped conduits has meansdefining openings in the wall thereof for atomizing the condensated fuelcollected on said lower conduit means to thereby define a postcarburetor for said condensated fuel.

14. Apparatus according to claim 12, wherein said upper conically shapedconduit means includes an annular flange extending radially outwardlytherefrom.

15. Apparatus according to claim 4, wherein said annular flange has aplurality of openings therethrough.

16. Apparatus according to claim 14, wherein said air regulating platemeans includes means defining an opening therethrough having annularrecesses surrounding both the upper and lower ends of said open mg;

wherein said concially shaped lower conduit means comprises a pair ofconcentric, conically shaped conduits defining a gap therebetween; andwherein the outer one of said lower conduit means has an annular flangethereon extending radially outwardly therefrom, said annular flanges onsaid upper and lower conduit means being received in said recesses insaid air regulating plate means.

17. Apparatus according to claim 1, wherein said fresh air supply meansis mounted directly on said means defining said carburetor duct.

18. Apparatus according to claim 17, wherein said fresh air supply meanscomprises a housing having bearing support means thereon and roll guidemeans in said housing, said roll guide means being secured to to saidbearing support means by nuts.

19. Apparatus according to claim 18, wherein an engaging lever iscoupled, via a preferably adjustable linkage means, to a connectionlever attached to a throttle flap shaft, said engaging lever extendingin parallel relationship to said connection lever.

20. Apparatus according to claim 18, wherein said roll guide means hastwo cutouts on its surface, one of which is, for the guide swivelmovement, in the fresh air supply tube area, whereas the other is formedas a form guide, the form and size of which is determined by the amountof fresh air required in the individual operating stages of an exhaustgas decontamination test.

21. Apparatus according to claim 20, wherein said roll guide means inits form guide and/or segment lever in its envelope curve are formed insuch a way that the amount of additional fresh air is precisely ratedthat a free oxygen content, or oxygen portion 0, in the exhaust gasleaving the cylinder of the engine, is guaranteed to be within thelimits of 0.5 to 2.0 vol.

22. Apparatus according to claim 18, including a fresh air supply tubethreadedly connected to said housing, said fresh air supply tube beingclosed at the entrance by a thin-mesh filter and secured in place by aperforated screw cover.

23. Apparatus according to claim 22, including a drain tube on thehousing connected to said downstream portion of said carburetor, saiddrain tube extending coaxially to the fresh-air supply tube, in ordersaid gap being adjustable by said threaded connection.

UNITED STATES PATENT orrrcr CERTIFICATE or CQRRECTWN Patent 3 759 499Dated September 18, 197.3

Inventor(s) Ludwig G. Lang It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Column 11, line 9; change "4" to--l4--=."

line 30; cancel to' (second occurrence) Signed and sealed this 16th dayof April 19714..

SEAL Attest:

EDI'JAHD M ,FLETCHER JR C MAR SHALL DANN Attesting Officer Commissionerof Patents F ORM P04 050 (10-69) USCOMlM-DC 6O376-P69 u.s. GOVERNMENTPRINTING orncs: I969 0-356-354,

1. Apparatus for decontaminating the exhaust gases produced by aninternal combustion engine by atomizing the fuel and varying theair-fuel ratio figure lambda , comprising: means defining a carburetorduct; a throttle flap in said carburetor duct means for accelerating theair-fuel mixture flow past said throttle flap along a first path; rimmeans on said throttle flap adjacent the periphery thereof forgenerating a vortex on the downstream side of said throttle flap alongsaid first path; means defining at least one bore in said rim means foraccelerating said air-fuel mixture flow in a streamlined manner pastsaid throttle flap in a second path intersecting said first path toeffect an elimination of said vortex and thereby provide a homogeneousmixture of said air and said fuel; air regulating plate means arrangeddownstream of said throttle flap means for carbureting the fuel whichhas condensed on the wall of said carburetor duct; and fresh air supplymeans for supplying additional air downstream of said throttle flapmeans.
 2. Apparatus according to claim 1, wherein said rim means variesin height along the length thereof.
 3. Apparatus according to claim 1,wherein said rim means extends along said periphery on one side of theaxis of rotation thereof.
 4. Apparatus according to claim 1, whereinsaid fresh air supply means comprises an opening in said air regulatingplate means.
 5. Apparatus according to claim 1, wherein the plane ofsaid throttle flap is perpendicular to the axis of said carburetor ductmeans when said internal combustion engine is at said idling speed. 6.Apparatus according to claim 1, wherein said rim means include meansdefining a plurality of nonradial openings therethrough so that theupper portion of said rim means shifts a large amount of air as comparedto the flat portion of said throttle flap means due to an increased flowdeflection of the air-fuel mixture ratio lambda in the direction oflambda > or =
 0. 7. Apparatus according to claim 6, wherein said rimmeans includes means defining a sharp edge for producing a vortex insaid air-fuel mixture downstream of said throttle flap means; andwherein said bore means in said rim means produce streamlined jetsdownstream of said throttle plate means to eliminate said vortex andthereby cause a homogenization of the air-fuel mixture throughout thedownstream cross section of said carburetor duct means.
 8. Apparatusaccording to claim 1, including a conventional bypass bore in said ductmeans adjacent said throttle flap means and a protuberance on the upperside of said throttle flap means and adapted to at least partially blocksaid conventional bypass bore for the purpose of reducing the fuelsupply when said internal combustion engine is at idle speed. 9.Apparatus according to claim 8, including a sniffle valve on saidthrottle flap.
 10. Apparatus according to claim 1, wherein said freshair supply means comprises a segment lever which can be actuatedsynchronously by a connection with the operating linkage of thecarburetor.
 11. Apparatus according to claim 10, wherein said segmentlever preferably has an envelope curve for the throttle flap swivelrange which concerns the exhaust gas decontamination for the regulationof the amount of time-intervalled additional fresh air, whereby theidling position remains fully covered.
 12. Apparatus according to claim1, wherein said air regulating plate means includes a pair of conicallyshaped upper and lower conduit means.
 13. Apparatus according to claim12, wherein said conically shaped lower conduit means comprises a pairof concentric conically shaped conduits defining a gap therebetween; andwherein the inner one of said conically shaped conduits has meansdefining openings in the wall thereof for atomizing the condensated fuelcollected on said lower conduit means to thereby define a postcarburetor for said condensated fuel.
 14. Apparatus according to claim12, wherein said upper conically shaped conduit means includes anannular flange extending radially outwardly therefrom.
 15. Apparatusaccording to claim 4, wherein said annular flange has a plurality ofopenings therethrough.
 16. Apparatus according to claim 14, wherein saidair regulating plate means includes means defining an openingtherethrough having annular recesses surrounding both the upper andlower ends of said opening; wherein said concially shaped lower conduitmeans comprises a pair of concentric, conically shaped conduits defininga gap therebetween; and wherein the outer one of said lower conduitmeans has an annular flange thereon extending radially outwardlytherefrom, said annular flanges on said upper and lower conduit meansbeing received in said recesses in said air regulating plate means. 17.Apparatus according to claim 1, wherein said fresh air supply means ismounted directly on said means defining said carburetor duct. 18.Apparatus according to claim 17, wherein said fresh air supply meanscomprises a housing having bearing support means thereon and roll guidemeans in said housing, said roll guide means being secured to to saidbearing support means by nuts.
 19. Apparatus according to claim 18,wherein an engaging lever is coupled, via a preferably adjustablelinkage means, to a connection lever attached to a throttle flap shaft,said engaging lever extending in parallel relationship to saidconnection lever.
 20. Apparatus according to claim 18, wherein said rollguide means has two cutouts on its surface, one of which is, for theguide swivel movement, in the fresh air supply tube area, whereas theother is formed as a form guide, the form and size of which isdetermined by the amount of fresh air required in the individualoperating stages of an exhaust gas decontamination test.
 21. Apparatusaccording to claim 20, wherein said roll guide means in its form guideand/or segment lever in its envelope curve are formed in such a way thatthe amount of additional fresh air is precisely rated that a free oxygencontent, or oxygen portion O2 in the exhaust gas leaving the cylinder ofthe engine, is guaranteed to be within the limits of 0.5 to 2.0 vol. %.22. Apparatus according to claim 18, including a fresh air supply tubethreadedly connected to said housing, said fresh air supply tube beingclosed at the entrance by a thin-mesh filter and secured in place by aperforated screw cover.
 23. Apparatus according to claim 22, including adrain tube on the housing connected to said downstream portion of saidcarburetor, said drain tube extending coaxially to the fresh-air supplytube, in order to transmit quantitatively regulated additional fresh airto said downstream portion of said carburetor duct means.
 24. Apparatusaccording to claim 23, including a gap between said fresh air supplytube and said drain tube, said gap being adjustable by said threadedconnection.